% hw=hann(20000);
nfft=size(SD_2,1);
kw=kaiser(nfft,20);
%f=fft(SD_2,500);
fs=7.94e8;
b=15e6;

p=pwelch(SD_2,kw,[],nfft,fs);
loglog(p);

t=1/(b/nfft);
b2=b/(fs/nfft);

signal=sum(p(28:41)) % signal
noise=sum(p(1:round(b2)))-signal % noise
10*log10(signal/noise)


% 3.3333e-005